Showing papers by "Weizmann Institute of Science published in 1981"
TL;DR: These lines were found to recognize foreign or self antigens in association with accessory cells of syngeneic major histocompatibility complex genotype and it is possible to study biological function as well as antigen specificity using T cell lines.
Abstract: The isolation and propagation of functional antigen-specific lines of T lymphoblasts is described. These lines were found to recognize foreign or self antigens in association with accessory cells of syngeneic major histocompatibility complex genotype. Intravenous inoculation of a T cell reactive only against myelin basic protein led to development of clinical paralysis in syngeneic rats. Thus, it is possible to study biological function as well as antigen specificity using T cell lines.
931 citations
TL;DR: Analysis of the pattern of residue to residue contacts at the interface of 50 helix to helix packings observed in ten proteins of known structure supports a model for helix-to- helix packing in which the ridges and grooves on the helix surface intercalate.
540 citations
TL;DR: It is reported here that attenuation of this cell line provides an agent for establishing resistance to induction of active EAE, and when suitably attenuated can be used as effective vaccines.
Abstract: Despite differences in initiating events and pathophysiology, the aetiological agents of all autoimmune diseases are lymphocytes specifically reactive against normal constituents of the individual. Recently we have isolated and grown as a cell line rat T lymphocytes reactive against myelin basic protein (BP)1. This T-cell line originated from rats in which we had induced experimental autoimmune encephalomyelitis (EAE) by immunizing them against BP. Inoculation of syngeneic rats with the T-cell line led to the relatively rapid onset of EAE1. We report here that attenuation of this cell line provides an agent for establishing resistance to induction of active EAE. Intravenous (i.v.) inoculation of syngeneic rats with cells of the line attenuated by treatment with irradiation or mitomycin C augmented resistance to EAE caused by an encephalitogenic challenge with BP. Thus, aetiological agents of autoimmune disease, like those of microbial disease, when suitably attenuated can be used as effective vaccines.
539 citations
TL;DR: It is suggested that water molecules have to crystallize on the charged phospholipid interface during the rapid freezing in order to allow the fusion process to take place and to give a few examples of ionophore-mediated ion transport reactions which give rise to accumulation of protons and Ca ions inside the lipsomes.
361 citations
TL;DR: The law governing the experimental temperature dependence of the relaxation time of spin glasses τ −1 = ƒ o exp [ −A (T −T o ) ] is interpreted in terms of interactions between the magnetic clusters constituting them as mentioned in this paper.
321 citations
13 Jul 1981
TL;DR: The method of well founded structures for proving termination of programs is extended to concurrent programs and different versions of fairness are introduced: Impartiality, Fairness and Justice.
Abstract: The method of well founded structures for proving termination of programs is extended to concurrent programs. The more complicated case is when a program terminates only for fair executions. Different versions of fairness are introduced: Impartiality, Fairness and Justice, and Methods for proving their termination are presented.
318 citations
TL;DR: In this paper, the authors give asymptotic values for the sums S ( β ) l ( n ) in the representations of the symmetric and the general linear groups, in combinatorics and in PI algebras.
285 citations
TL;DR: In this article, the axial anomaly of three-point functions of colour singlet currents in quark confining theories implies the presence of zero-mass bound states in the physical spectrum.
218 citations
TL;DR: The results suggest that in addition to the mediation by prostaglandin E 2, thromboxane A 2 and prostacyclin I 2 may also be involved in the inflammatory response in ulcerative colitis.
201 citations
TL;DR: In this paper, necessary and sufficient conditions for an invertible block matrix to admit a block triangular factorization are established for the particular choice m = n −1. And the special case in which the given R ij are positive definite (in an appropriate sense) is explored in detail.
189 citations
TL;DR: Proteins and carbohydrates were long considered distinct classes of natural products, and most chemists and biochemists had little doubt about which of the two deserved greater attention.
Abstract: Proteins and carbohydrates were long considered distinct classes of natural products, and most chemists and biochemists had little doubt about which of the two deserved greater attention. This atti...
TL;DR: It is found that cells spreading on a substrate coated with rhodamine-labeled fibronectin progressively removed the underlying protein from the substrate, with implications on the dynamics of cell spreading and locomotion.
TL;DR: Conformational energy calculations have been used to study the role of the proline residues in the folding of bovine pancreatic trypsin inhibitor, suggesting that rapid folding to a stable native-like conformation can occur with either isomeric form.
TL;DR: In this paper, a composite model for quarks and leptons based on an exact SU(3)C × SU (3)H gauge theory and two fundamental J = 1 2 fermions: a charged T-rishon and a neutral V-rishons was proposed.
TL;DR: The quasielastic laser light scattering discloses little information about dynamics of internal motion of DNA chains, and the regimes in which a dependence of the correlation decay times on q3 rather than q2 applies are presented.
Abstract: We show that the persistence length a of DNA, derived from total intensity laser light scattering of linear Col E1 DNA and corrected for excluded-volume effects, varies from about 68 nm in 0.005M NaCl to about 40 nm in 0.2M NaCl, leveling off to a constant value (about 27 nm) at high NaCl (1–4M) concentration. These observations do not agree with current views on the effect of electrostatic charge and ionic conditions on DNA dimensions. The apparent diffusion constant Dapp, determined from laser light scattering autocorrelation as a function of scattering vector q, at NaCl concentrations 0.005–4M, correctly yields the translational diffusion coefficient Dt at low values of q and scales with molecular dimensions rather than segment length at high values of q; thus, Dapp/Dt yields a universal curve when plotted against q2R, where Rg is the radius of the gyration. The sedimentation coefficients s at 0.1 and 0.2M NaCl concentration closely agree with the well-tested empirical relations, and a combination of s, Dt, and the appropriate density increments yield correct molar masses over the whole salt concentration range. Approximate constancy of DtRg indicates limited draining in translational flow. We present some observations and thoughts on the regimes in which a dependence of the correlation decay times on q3 rather than q2 applies. We conclude that quasielastic laser light scattering discloses little information about dynamics of internal motion of DNA chains.
01 May 1981
TL;DR: Propositional Temporal Logic is applied to the specification and synthesis of the synchronization part of communicating processes by constructing a model of the given specifications using a tableau-like satisfiability algorithm for PTL.
Abstract: In this paper, we apply Propositional Temporal Logic (PTL) to the specification and synthesis of the synchronization part of communicating processes. To specify a process, we give a PTL formula that describes its sequence of communications. The synthesis is done by constructing a model of the given specifications using a tableau-like satisfiability algorithm for PTL. This model can then be interpreted as a program.
TL;DR: (Na,K)ATPase from kidney membranes has been reconstituted into proteoliposomes following solubilization in cholate, by the freeze—thaw sonication procedure described by Kasahara & Hinkle (1977).
Abstract: 1. (Na,K)ATPase from kidney membranes has been reconstituted into proteoliposomes following solubilization in cholate, by the freeze-thaw sonication procedure described by Kasahara & Hinkle (1977). The method is rapid and convenient.2. Upon addition of ATP to the exterior medium the reconstituted vesicles sustain high rates of active (22)Na uptake and (86)Rb efflux with many properties similar to those of the Na/K pump in well characterized cells such as erythrocytes.3. Observations on both active and passive transport of (22) Na and (86)Rb indicate that the vesicle population is heterogeneous; about 40 per cent contain Na/K pumps and the remainder seem to be plain lipid vesicles.4. The major Na(+)- or K(+)-stabilized non-phosphorylated conformational forms of the (Na, K)ATPase, E(1). Na and E(2). (K) respectively, have been investigated in the proteoliposomes, with particular regard to sidedness of the actions of Na(+) and K(+).5. Tryptic digestion of the vesicles reveals the Na(+)- and K(+)-stabilized conformations E(1). Na and E(2). (K) as characterized originally for purified (Na, K)ATPase (Jorgensen, 1975). Controlled trypsinolysis of Tris(+)-loaded vesicles in a Na(+)-or K(+)-containing medium leads to typical biphasic (Na(+)) or simple exponential (K(+)) time courses respectively, for loss of ATP-dependent (22)Na uptake (assayed subsequent to the tryptic digestion in the presence of inophores valinomycin plus FCCP). Tryptic digestion of K(+)- or Rb(+)- or Tris(+)-loaded vesicles suspended in a Na(+) medium results only in the biphasic (E(1). Na) pattern of loss of ATP-dependent (22)Na uptake.6. ATP-dependent (22)Na uptake and (86)Rb efflux are reduced by about the same extent following a short tryptic digestion in a Na(+)-containing medium.7. Vanadate ions inhibit ATP-dependent (22)Na uptake into the vesicles, at low concentrations (K(0.5) approximately 2 x 10(-7)m), following pre-incubation together with Mg(2+) and K(+) ions. K(+) ions in the medium are effective, K(+) ions within the vesicle are not. Na(+) ions in the medium prevent inhibition by vanadate+Mg(2+) but do not reverse inhibition in vesicles pre-incubated with vanadate, Mg(2+) and K(+) ions.8. The results show that the conformational forms E(1). Na and E(2). (K) are stabilized by Na(+) or K(+) ions respectively, bound to sites on the Na/K pump normally facing the cytoplasm. The significance of this finding is discussed in relation to the cation transport function of the pump.
TL;DR: In this article, a formal expression for high-temperature series for models with O(N) and cubic symmetry, with a special form of nearest neighbor interactions on the honeycomb lattice, was derived.
TL;DR: The results indicate that mating is a biological stimulus for the release of endogenous opoids, possibly to prevent intense sexual stimulation from becoming aversive, and increase its reward value.
TL;DR: An exact and approximate realization theory for estimation and model filters of second-order stationary stochastic sequences is presented, and how the techniques presented constitute a generalization of many aspects of the Levinson-Szego theory of partial realizations is shown.
Abstract: An exact and approximate realization theory for estimation and model filters of second-order stationary stochastic sequences is presented. The properties of J -lossless matrices as a unifying framework are used. Necessary and sufficient conditions for the exact realization of an estimation filter and a model filter as a submatrix of a J -lossless system are deduced. An extension of the so-called Schur algorithm yields an approximate J -lossless realization based on partial past information about the process. The geometric properties of such partial realizations and their convergence are studied. Finally, connections with the Nevanlinna-Pick problem are made, and how the techniques presented constitute a generalization of many aspects of the Levinson-Szego theory of partial realizations is shown. As a consequence generalized recursive formulas for reproducing kernels and Christoffel-Darboux formulas are obtained. In this paper the scalar case is considered. The matrix case will be considered in a separate publication.
TL;DR: It is proved that a natural generalization of chess to an n × n board is complete in exponential time and implies that there exist chess positions on ann × n chessboard for which the problem of determing who can win from that position requires an amount of time which is at least exponential in n.
TL;DR: It was found that EGF induced striking changes in the distribution of actin and α-actinin within human epidermoid carcinoma cells, and upon prolonged incubation for 8 h or more in the presence of EGF, the normal, well organized patterns of act in and α in these cells were restored.
TL;DR: It is demonstrated that FITC specifically blocks the ATP binding site of the Ca2+-ATPase from sarcoplasmic reticulum and does not prevent the phosphorylation of the enzyme by Pi or Ca2-uptake with acetyl phosphate as a substrate.
TL;DR: In this article, the phase separation behavior of thin films on glass appears to be the result of two kinds of substrate-polymer interactions in addition to the geometrical effect: electrostatic interaction of the charged glass surface (a destabilizing effect at all film compositions) and selective adsorption of polystyrene on glass.
Abstract: Films of polystyrene-poly(vinylmethyl ether) blends of various compositions are formed by a dip-coating procedure, the thickness of the film being controlled by the concentration of the solution. The substrates used are glass and gold. The phase separation process is followed by a laser light scattering experiment in which the total forward scattering intensity is monitored as a function of temperature. Morphological examination shows that phase separation occurs by a spinodal decomposition mechanism. A thickness effect on the phase separation temperature is noticeable when film thickness is smaller than 1 μm. This effect is substrate dependent. In all films formed on gold the spinodal temperature increases as film thickness decreases. Films formed on glass exhibit a destabilizing effect on decreasing film thickness. This effect is slight in films of composition poorer in polystyrene than the critical composition, and is enhanced in films richer in polystyrene. The stabilizing effect of decreasing the thickness of films formed on the gold substrate is considered to reflect mainly a purely geometrical effect. The decreasing dimensionality is shown by simple theoretical considerations to increase the phase-separation temperature. However, the phase separation behavior of thin films on glass appears to be the result of two kinds of substrate-polymer interactions in addition to the geometrical effect: (a) electrostatic interaction of the charged glass surface (a destabilizing effect at all film compositions) and (b) selective adsorption of polystyrene on glass.
TL;DR: In this article, the effect of interactions between cascade particles in the intranuclear cascade model of high-energy heavy ion reactions was investigated and the results showed that the "single knockout" nucleons are only a small fraction of the inclusive spectra.
Abstract: Interactions between cascade particles were included in our intranuclear cascade calculation for high energy heavy ion collisions. This leads to better agreement between the calculated and experimental results for the inclusive pion cross sections and for two-nucleon correlations, without changing appreciably the calculated inclusive proton cross sections. The "single knockout" nucleons are shown to be a small fraction of the inclusive spectra.[NUCLEAR REACTIONS Calculated effect of interactions between cascade particles in the intranuclear cascade model of high-energy heavy-ion reactions. Inclusive proton and pion cross sections and two-particle correlations. $E=400\ensuremath{-}1050$ MeV/nucleon. $^{12}\mathrm{C}$+$^{12}\mathrm{C}$, $^{40}\mathrm{Ar}$+$^{40}\mathrm{Ca}$, $^{40}\mathrm{Ar}$+$^{40}\mathrm{Ar}$, $^{20}\mathrm{Ne}$+$^{238}\mathrm{U}$, $^{40}\mathrm{Ar}$+$^{208}\mathrm{Pb}$.]
TL;DR: The production of large amounts of glycerol and s-carotene by Dunaliella has made it a model organism to study the biological utilization of solar energy in the production of chemicals of industrial interest.
TL;DR: Vitamin D3 deficient mice show a depressed inflammatory response and both inflammatory peritoneal macrophages and bone marrow polymorphonuclear leukocytes of D− mice exhibit a decreased spontaneous migration under agarose.
Abstract: Vitamin D3 deficient (D−) mice show a depressed inflammatory response and both inflammatory peritoneal macrophages and bone marrow polymorphonuclear leukocytes of D− mice exhibit a decreased spontaneous migration under agarose. The impaired phagocytic response of peritoneal macrophages from D− mice can be corrected by incubation with 1,25-dihydroxyvitamin D3 and is not affected by interaction with other vitamin D3 metabolites. Transfer of mice from the D− to the D+ state results in correction of both the inflammatory and the phagocytic response. Intactness of phagocyte function is thus directly dependent on vitamin D3 metabolism.
TL;DR: An assay has been developed to measure an interferon-induced enzyme in white blood cells that is constant in healthy subjects but increases by 2-10 times in 85% of patients with acute viral infections.
TL;DR: In this paper, the authors give a systematic treatment of the exact and approximate realization of a positive real matrix-valued function on the open unit disc by means of a lossless circuit connected to a passive load.
Abstract: In this paper we give a systematic treatment of the exact and approximate realization of a positive real matrix-valued function on the open unit disc by means of a lossless circuit connected to a passive load. We discuss the mathematical properties of the chain scattering matrix which describes the lossless circuit and rederive a form of the classical Darlington synthesis theorem generalized to roomy matrix-valued transmission functions. We then develop a matrix version of an algorithm due to Schur for the construction of approximate realizations which produces (minimal degree) Nevanlinna–Pick approximants to the original positive real matrix. We further identify the normalized inverse of one of the outer factors of the approximant to the positive real matrix as the orthogonal projection of the identity onto a suitably defined subspace, give its interpretation as a reproducing kernel, and establish strong convergence under mild conditions on the growth of the order of the approximation. Finally we interpret and apply the mathematical theory developed in the body of the paper to the theory of prediction for vector-valued second order stationary stochastic sequences and briefly discuss connections with the theory of maximum entropy extensions and of inverse scattering.